Do You Know What Your Thermostat Fan Should Be Set To?
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Do You Know What Your Thermostat Fan Should Be Set To?


Normally, you set the thermostat to heat when it’s too cold and you’d want a little more heat within your rooms, and set it to cool especially in the summer when the interiors are a bit too hot for your comfort. And during the periods of the year when you need neither the heating nor the air conditioning, you simply set the thermostat to “off.” It’s that simple.

What about the thermostat fan? Typically, you can set the fan to “on” or “auto” but which is which and when should you apply which control?

The Thermostat Fan in an “On” State

Setting the thermostat fan “on” keeps it running all day, every day, regardless of the cooling or heating setting.


  • Better distribution of air resulting in increased comfort.
  • Longer working life due to less stops and starts.
  • Filters the air in your home.


  • Running the fan all day is very expensive.
  • Filters clog up quickly. Maintenance and frequent replacement can be quite expensive.
  • In colder seasons, a running fan leaves us with a “colder” feeling though in reality there is never a difference in room and space temperatures.

Setting the Thermostat Fan to “Auto”

In this setting, the fan will only turn on when it receives a signal from the furnace.


  • You save energy because fans run for shorter times and at comparably lower speeds.
  • Filters last longer because of reduced usage.


  • Air isn’t as evenly distributed as when the fan is in an On state.
  • Due to more starts and stops your fans wear out much faster.


Roth Heating and Cooling is a Portland, Oregon based heating and cooling company. Contact us today to learn more about our products and services or request a free quote and take advantage of our unbeatable prices.

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